Transcript Chapter 7
Quantum Mechanical Model
CHM 108
SUROVIEC
FALL 2015
I. Quantum Mechanics
2
Small is a relative term, but we use it to show size.
There is a limit to how we can use it in science.
II. Nature of Light
3
A. Wave Nature of light
Light is electromagnetic radiation. A type of energy
embodies in oscillating electric and magnetic fields
A. Wave Nature of Light
4
An EM wave can be characterized by its amplitude
and wavelength.
A. Nature of Light
5
All waves are also characterized by frequency (n)
B. The EM Spectrum
6
The EM Spectrum is made of several different
wavelengths
C. Interference and Diffraction
7
Waves (including EM waves) interact with each
other in a characteristic way called interference
07_06.JPG
8
D. Particle Nature of Light
9
In the early 1900s light was believed to be wave only,
but then the photoelectric effect was discovered.
Example
10
A DVD player uses a laser that emits light at 685nm.
What is the energy of 1 mole of photons of this light?
III. Atomic Spectroscopy and the Bohr Model
11
The dual nature of light led scientists to think about
how light acts as both a particle and as a wave.
Atomic Spectroscopy was developed to explore the
phenomenon.
07_10.JPG
12
III. Atomic Spectroscopy and the Bohr Model
13
The idea that each element has discreet lines
required scientists, like Neils Bohr, to develop a new
model for the atom.
IV. Wave Nature
14
It has been shown that the wave nature of an
electron is an inherent property of an individual
electron.
A. deBroglie Wavelength
An electron traveling through space has a wave
nature.
Example
15
Calculate the wavelength in nm of an electron with
speed 4.57 x 106 m/s
B. Uncertainty Principle
16
Experiments have shown that we can never see the
interference pattern and simultaneously determine
which hole the electron goes through to make it.
C. Indeterminacy
17
Macroscopic objects have their velocity and position
known : determined.
Electrons do not (Uncertainty Principle):
indeterminacy
V. Quantum Mechanics and the Atom
18
Many properties of an element is dependent on the
energy of electrons which is related to the velocity
which we have shown to be indeterminate.
A.Schrodinger Equation
The wave function ψ is away to describe energy of
electrons and the probability of finding an electron
in a volume of space.
1. Principle Quantum Number (n)
19
The integer that determines overall size and energy
of an orbital.
2. Angular Momentum Quantum Number (l)
20
This number determines the shape of the orbital.
2. Angular Momentum Quantum Number (l)
21
3. Magnetic Quantum Number (ml)
22
This number tells us the orientation of the orbital
ml = -1
ml = -2
ml = 0
ml = -1
ml = 0
ml = 1
ml = 1
ml = 2
4. Magnetic Spin Number (ms)
25
The spin of the electron in the orbital
Examples
26
How many 2p orbitals are there in an atom?
How many electrons can be placed in the 3d
sublevel?